(a) Field of the Invention
A present invention relates to an iris recognition technology for identifying person and, in particular, to an iris identification system and method, and a computer readable storage medium stored thereon computer executable instructions to implement the iris identification method, that are capable of improving an iris recognition accuracy using reference iris images taken in the various environments.
(b) Description of the Related Art
Recently, various biometric identification technologies using fingerprint, voice, iris, and vein patterns have been developed. Among them, the iris identification technology is known to provide the most secure identification reliability in the security field.
Such an iris identification technology is well known in the art as disclosed by International Publication No. WO94/9446 entitled “Biometric Personal Identification System Based On Iris Analysis.”
This prior art discloses the iris identification technique which is performed in such a way of acquiring an image of the eye to be analyzed in digital form suitable for analysis, defining and isolating the iris portion of the image, analyzing the defined area of the image so as to produce an iris code, storing the iris code as a reference code, and comparing a presented code with the reference code to obtain a Hamming distance through the exclusive-OR logical operation. The Hamming distance is used in order to determine the identity of a person and to calculate confidence level for the decision.
However, this prior art has some drawbacks in that it is difficult to consistently adopt the polar coordinates system to the iris identification since the pupil is constricted when exposed to bright light and expanded in dim light (see FIG. 1A) and the constriction/expansion degree to the light differs in every person because each person has his/her own characteristics in sphincter papillae, dilator papillae, intraocular pressure, and etc., such that it is also difficult to predict how an iris characteristic factor of the iris 1 changes when the pupil 2 expands (see FIG. 1B). Referring to FIG. 1B, when an iris image having a characteristic factor 3 is presented and compared with one of the reference iris images, it might be determined that there is no identical reference iris image.
Also, since the iris identification of the prior art divides the iris image so as to define annular analysis portions, this identification accuracy considerably decreases when this technique is used for Asian people whose eye is exposed a little relative to the westerners. If narrowing the analysis band in order to prevent this problem, security reliability is seriously degraded.
Furthermore, this prior art of the iris identification technique has no algorithm capable of preventing misidentification by an inorganic fake iris.